I can't exactly pin point your symptoms to Bi-polar becaue at your age it could be a few things so it's hard to say. Young girls can either have very mild PMS to extreme PMS. I use to get so frustrated with my friends in high school when they would pass their Bi&*ie moods off on PMS I would think the phrase was just used as an excuse. It was not until after my first son that I realized that it was a true statement and more so after my second son and divorce it became worse that I am now medicated for Extreme PMS because of unexplainable yelling fits, crying, instant depression with no cause and it would be a rollercoaster happy, sad, mad all with in a matter of 30min.
Another thing that girls of your age (and guys for that matter) get to the point of being burnt out. You have been in school for 12 years now, friends with the same crowd, (lots of drama in high school), your parents are unfair, unreasonable, paranoid, and always on your case about something. (am I right??) You want a change. All of this can cause the feelings that you are having as well. Even I at the age of 30 have times like this but of course in different circumstances.
As a teenager your emotions are racing a 100mph and its hard to stop and get off the roller coaster. Most teenagers have a lot going on around them and with in them. Your probably stressing about grades, getting in trouble with your parents, friends fighting with eachother or with you, wanting the school year to be over, wanting to expierence life, taking on not only your problems but also helping others with theirs. I could be off base but I know that these were my troubles and I have a 16 year old step daughter who seems to complain about these problems.
With the things that I have mentioned you could also be having a bit of depression this is OK many girls of your age go through some kind of depression and you will get through it. You just need to look at the positive side of things such as school is almost out just a few more months to go, you have a support group, use them, your boyfriend and your closest friends the ones you can really trust lean on them they can be helpful. And though you may not think so, so are your parents. They love you and they are there to protect you. I know that is hard to see now but you will especially after you have kids of your own. I gained more respect for mine after having kids and I hated them when I was a teenager. Hey and if you want to talk you can always find really great people to talk to on here and you can PM me anytime and I will talk to you.
You will get through this I promise and I don't think your Bi-polar (my husband is so I know a few of the signs) I think your just on the roller coaster of life and it slows down "sometimes" I promise. Feel free to talk to me anytime. Good luck